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Dana Jansens
9a6c74f0cd
`FindIfOrNull` returns a pointer to the element in the range if it's found, and nullptr otherwise. `FindIfOrNone` returns a copy of the element in the range if it's found, and `T::None` (for a range of elements of type `T`) otherwise. `Contains` returns a bool indicating whether the element in the range is found. These functions replace `llvm::find()` and `llvm::find_if()` when you want a single answer back instead of an iterator. This avoids the need to check against `end()`, allowing the return condition to be tested as a standard bool. We replace uses of `find()` and `find_if()` that did not require an iterator with these new helpers. Note that the return type of `FindIfOrNull` is a pointer since we can not write `optional<T&>`, which must be tested for null. If the null check is omitted, UB occurs and the resulting code may end up with an incorrect pointer (https://crbug.com/40153300) into the range (or elsewhere), rather than a null dereference. And this would be very confusing to debug. Hopefully debug builds and sanitizers keep this from being an issue we sink a bunch of time into debugging.